Caster assemblies are generally well known in the art. Such wheeled casters are attached to a base or to the bottom of an object such as a bed, a stretcher, a gurney, a chair, a large piece of medical diagnostic equipment, a palette, a wagon, a cart, and the like. Caster assemblies typically have a single wheel or paired dual wheels and are configured to provide translation (rolling movement) of the object along a surface or the ground (once attached to the object). In some configurations, the wheel(s) of the wheeled caster assembly may be fixed in a single orientation relative to the attached object to provide motion in a single forward and backward direction. In other configurations, the caster assembly includes a swivel brake lock that allows the caster assembly to rotate about a vertical axis. If all caster assemblies attached to the object are of this configuration, the object to which the caster assembly is attached is able to move in a lateral as well as a forward and backward motion. Different configurations are also well known with combinations of fixed and swivel-enabled caster assemblies attached to a single object.
Wheel brake lock and swivel brake lock assemblies for casters are also well known and have been provided in a variety of forms for many years. A wheel brake lock assembly is typically used to stop the motion of the wheel(s) of a wheel assembly, such that the wheel(s) is/are no longer able to rotate about a respective wheel axis. Wheel brake lock assemblies are often engaged when a user wishes the object to remain in a fixed position. If the caster assembly has a swivel brake lock function, the object may still be able to rotate about the wheel-braked locked caster assembly eventhough the wheel(s) themselves is/are not able to rotate.
Similarly, swivel brake lock assemblies have been designed to lock a swivel-enabled caster assembly in a fixed orientation about its vertical swivel axis, such that the caster assembly is unable to swivel about that vertical axis. Swivel brake lock assemblies are commonly used when a user wishes to translate the object in a fixed direction, such as forward or backwards relative to the object, without having to exert the additional effort to steer in that direction. As only the swiveling about the vertical axis is locked when a swivel brake lock is engaged, the wheel(s) of the caster assembly is/are still free to rotate about the wheel axis. Furthermore, objects having fixed caster assemblies oriented in the same direction will generally travel in a straight line.
Additionally, a combination of a wheel brake lock and swivel brake lock assemblies in a caster assembly are known to simultaneously engage a wheel brake lock and a swivel brake lock using a single stopping actuator. With such a single actuator, the user is able with a single motion able to arrest the rotation of the caster assembly's wheel(s) about the horizontal wheel axis and to stop the rotation of the swivel about the vertical swivel axis.
While various combinations of these wheel and swivel brake assemblies and their associated functionalities are required in the art, each combination typically presents a challenge to combine together into a caster assembly that meets the space, actuation and service requirements of modern equipment manufacturers who incorporate caster assemblies into their products. As a result, it is required, in many cases, to custom design the various components of a caster assembly to meet the unique functional requirements of such manufacturers. That is, for example, a wheeled caster assembly required to have both a wheel brake lock assembly and a swivel brake lock assembly will, in the prior art, be structured differently from a caster assembly having only a wheel brake lock assembly, or only a swivel brake lock assembly. This is particularly problematic in relation to the yoke of the caster assembly, which yoke is the central support frame of a caster assembly on which most, if not all, of the other components of the caster assembly are mounted. To effectively carry out these support and mounting functions, most caster yokes used for heavy duty equipment applications, such as X-ray machines and CT scanners, are themselves typically large and robust, often being constructed as a monolithic metal fabrication or casting. As such, changing the design of a caster yoke in response to the need to mount more, or different, caster components thereon typically results in significant re-design and re-tooling costs.
Further, prior art caster assemblies, particularly larger caster assemblies such as mentioned in the previous paragraph, often have a molded plastic trim cover assembly mounted on, or over, the caster yoke to improve its aesthetic appearance and/or to ease its maintenance and/or cleaning requirements. Accordingly, performance requirement changes made by equipment manufacturers to the caster assemblies they order for their equipment may not only require significant changes to the structural parts and components used to manufacture the caster assemblies, but may additionally require significant re-design of the associated trim cover assemblies to accommodate their mounting on a revised caster assembly, which, in turn, may result in significant additional re-design and tooling costs.
One prior art wheeled caster assembly having caster components used to construct a unique caster configuration having a wheel brake lock assembly, a fixed-direction swivel lock assembly, and a full-directional swivel lock assembly is disclosed in U.S. Pat. No. 8,424,158 (Steenson), which patent is hereby incorporated by reference. The wheeled caster assembly disclosed in U.S. Pat. No. 8,424,158 includes a caster yoke and a cam assembly operable in at least three operational (functional) states (modes). The cam assembly may include an actuating mechanism for operating the cam assembly, a swivel lever mechanism and a brake lever mechanism in communication with a cam. When in a first operational (functional) state (mode), the wheel rotates freely and the caster yoke swivels freely. When in a second operational (functional) state (mode), a first swivel brake is engaged by the swivel lever mechanism to lock the caster yoke in a predetermined orientation while the wheel is allowed to rotate freely. When in a third operational (functional) state (mode), a wheel brake lock is engaged by the brake lever mechanism to stop the wheel from rotating freely, and a second swivel brake lock is simultaneously engaged to stop the caster yoke from swiveling. While operatively effective in its various operational (functional) states (modes), it will be appreciated by those skilled in the art that the Steenson prior art caster assembly is both complex and expensive to manufacture. Most importantly, such high levels of complexity and expense cannot be justified for many applications where less operational (functional) states (modes) are required. Moreover, the Steenson prior art caster assembly is not readily adaptable to the production of caster assemblies having less operational (functional) states (modes) without extensive redesign of the various caster components utilized therein, including the caster yoke, and of the associated tooling, facilities and other resources necessary to produce assemble and inventory such components. As a consequence, in order for a caster manufacturer to be able to offer its customers a full model line (set) of casters capable of offering all of the three different operational (functional) capabilities described above in their various combinations and permutations, it would be necessary for such manufacturer to construct and inventory as many as 9 different unique caster models, each having a plurality of parts, including caster yokes, that are potentially unique to each model of the line (set).
Reducing the cost of designing and manufacturing caster assemblies having different functionalities and inventorying the numerous different caster components used in their production represents an ongoing challenge for manufacturing efficiencies in response to continuing customer demands for reduced costs. Accordingly, there remains a need in the art for improved caster assemblies that may be produced in sets with different members of the set having different functional capabilities and without the need to re-design the various caster components to accommodate such differences in functionality.